高压下Al的零温电子结构和物态方程  

ELECTRONIC STRUCTURES ANDEQUATION OFSTATE FOR ALUMINIUM UNDER HIGH PRESSURE AT T=0K

作　　者：张春斌[1] 李绍孟 腾亚钢 

机构地区：[1]北京应用物理与计算数学研究所

出　　处：《高压物理学报》1994年第4期273-278,共6页Chinese Journal of High Pressure Physics

摘　　要：用ＬＭＴＯ方法（线性Ｍｕｆｆｉｎ－Ｔｉｎ轨道法），计算了金属铝的超高压电子结构及零温物态方程。Ａｌ的压缩比到１０，压力达１０ＴＰａ。根据第一原理计算结果，在带结构方面，Ｓ带总是处于Ｆｅｒｍｉ能以下，随着压力的增加，ｓ、ｐ和ｄ的带宽增加，随后则杂化程度增加，所以ｓ、ｄ轨道的电子占据数连续变化。上述变化对压力的影响也是连续的，换言之，从ｓ→ｄ转变没有理由说明Ａｌ在０．５ＴＰａ附近冲击Ｈｕｇｏｎｉｏｔ的斜率的拐弯现象。而这一点则是与Ａｌ＇ｔｓｈｕｌｅｒ的观点不同。物态方程的第一原理计算结果表明，ｂｃｃ结构比ｆｃｃ结构要软，但因差别不很大，即使发生ｆｃｃ→ｂｃｃ的转变，也不会引起Ｈｕｇｏｎｉｏｔ的质的变化（拐弯）。Ａｌ的ＬＭＴＯ物态方程还表明，我们以前所采用的半经验的冷压误差可达３０％。为此，根据ＬＭＴＯ结果，给出新的冷压表达式其中ａ＿０＝－７．３２７７９，ａ＿１＝１８．７５４３，ａ＿２＝１０．２０９７，ａ＿３＝－２．５２３５３，ａ＿４＝－４．７８７２，ａ＿５＝６．０６５９４拟合误差小于３％。The study for Al up to the pressure p=10 TPa ,the compression Ω_0/Ω=10 , by using the first principle ealculations is performed. The energy band structures and electronic occupation numbers of the states for a series of lattice constants are pre-sented.It follows from the energy band structures that S band always lies below the Fermi level. As the pressure increases ,the bandwidths of ,s, p and d increase ,then the degree of hybridization become higher. So the electronic occupation numbers of s , d or-bitals change continuously. The effect of above mentioned changes to pressure is contin-uous too. In other words ,s→d transition is not the reason for a break in the slope of the shock Hugoniot for Al near 0.5 TPa,as claimed by Al' tshuler. The equation of state at T=0K shows that bcc structure is softer than fcc.The results calculated by LMTO are different from the semiempirical ones given by us previously. A new correct fitting for EOS from the results of LMTO is presented.

关 键 词：高压 物态方程 电子结构 铝 零温度 

分 类 号：O521.2[理学—高压高温物理]